Salvo squeezebore projectiles



June 17, 1969 R, s. ROBINSON 3,450,050

SALVO SQUEEZEBORE PROJECTILES Filed Aug. 4, 1961 jr-( g; 0

United States Patent O 3,450,050 SALVO SQUEEZEBORE PROJECTILES Russell S. Robinson, Newport Beach, Calif., assignor to Colts Inc., Hartford, Coun., a corporation of Arizona Filed Aug. 4, 1961, Ser. No. 129,401 Int. Cl. F42b 13/00, 11/00 U.S. Cl. 102-92.4

4 Claims This invention relates to new and improved salvo projectiles of the class adapted for tiring from a squeeze or taper-bored rearm.

The objects of the invention are means by which a salvo of projectiles may be red from a single taper-bored barrel during each discharge, means by which the said projectiles are loaded into the firearm as a single assembly before discharge, means by which said projectiles mutually disassemble during shot travel and emerge separately from the barrel muzzle upon discharge, and means for achieving high velocity and a high order of accuracy and range in each of a salvo of projectiles tired during a single discharge.

Squeezebore guns are guns of known class in which the breech end of the bore is substantially larger in diameter than the muzzle end, the length of bore between breech and muzzle incorporating a taper which forces the diametral reduction of the projectile during shot travel. Squeezebore guns of krown construction may be rifled or smoothbore, and the tapered portion of the bore may take one of several forms. The form referred to in the following examples comprises a rifled cylindrical bore or full bore at the breech end, said bore merging into a smoothbore conical taper toward the muzzle, said taper terminating in a relatively short smooth-bore sub-caliber cylindrical bore adjacent to the muzzle. The invention is applicable, however, to other forms of ried or smooth-bore squeezebore guns.

squeezebore ammunition projectiles of known construction usually comprise a sub-caliber projectile body having two annular skirts of substantially truncated conical form which are rigidly connected thereto, said skirts being adapted to lill the annular void between the sub-caliber projectile body and the full bore of the gun. Usually a forward and a rear skirt are employed, the forward skirt being primarily used for stabilizing the projectile against longitudinal instability in the form of pitching movements while same is in the barrel, the rear skirt being used for sealing the projectile in the barrel bore against escape of propellant gasses. In a ried squeezebore gun form, one or both skirts may be adapted to be engraved by the rifling and to receive the torque applied to the projectile thereby. A cannelure is usually formed in the sub-caliber projectile body to the rear of the front skirt in known type squeezebore projectiles, said cannelure being adapted to receive the forward skirt during the nal phase of the squeezing operation so that a reasonably smooth exterior surface is provided for the projectile after it emerges from the barrel.

In squeezebore firearms and ammunitions of known construction, it is essential to vent away the air enclosed in the annular volume between the front and rear skirts of the projectile during the squeezing operation. Said venting is usually performed according to the known art either by providing a multiplicity of small holes in the tapered portion of the barrel which communicate with the outside atmosphere, or by forming air escape holes in the forward skirt of the projectile, both forms enabling escape of the enclosed air during the squeeze operation. Without such air venting means, an almost explosive pneumatic pressure is built up between the forward and rear skirts which is usually sufficient to rupture the projectile or the gun barrel.

3,450,050 Patented June 17, 1969 ICC In squeezebore projectiles according to this invention, each projectile is an essembly comprising a plurality of axially disposed sub-projectiles adapted for salvo tiring. Said sub-projectiles may be substantially similar or dissimilar, but according to the invention said sub-projectiles mutually cooperate and are rigidly interconnected before ring and usually during manufacture so as to enable the loading of the assembly as a single component into the breech of the firearm, the interconnecting means between adjacent sub-projectiles being adapted to rupture during the propulsion of the said assembly as itis propelled along the bore of the barrel.

Each sub-projectile of the assembly has a sub-caliber body having a diameter substantially equal to that of the sub-caliber bore at the muzzle end of the barrel so that said body substantially cooperates with said sub-caliber bore during its passage through same with negligible deformation.

Each sub-projectile of the assembly is also provided with a skirt usually of conical form which is rigidly connected to the rear of the said body, said skirt having a maximum diameter which usually slightly interferes with the full bore of the barrel in such manner as to form a gas seal within said bore and to engrave with respect to the rifling therein.

In some projectile assembly forms according to the invention in which the ratio of full bore to sub-caliber bore may be relatively small or where the mass or number of sub-projectiles per assembly is small, a simple skirt having the form of a substantially conical flare may be used. In other projectile assembly forms according to the invention in which the ratio of full bore to sub-caliber bore may ybe large or where the mass or number of sub-projectiles per assembly may be large, a relexed skirt may be used within the a-mbit of the invention, in which the outer periphery of the skirt of each sub-projectile is provided with a rearwardly-extending cylindrical element, which, in the case of leading sub-projectiles in an assembly, is adapted to cooperate with the skirt of following sub-projectiles for the purpose of receiving a portion of the propulsive thrust, and which, in case of the rearmost sub-projectile in an assembly, is adapted to provide more obturating and engraving area with respect to the barrel bore.

The single skirt of each sub-projectile of said assembly is formed of a material and to such a contour as will enable said skirt to be inwardly deformed without rupture and without excessive absorbtion of energy during the passage of said sub-projectile down the tapered portion of the barrel until the maximum diameter of said skirt is so reduced as to substantially equal the diameter of the subcaliber body of said sub-projectile.

Each sub-projectile of a projectile assembly may be formed of a single homogeneous piece of material in which the forward portion of the body may be surface or otherwise hardened, or may alternatively be formed of a plurality of components rigidly connected together such as, for instance, a hardened core within the body of the sub-projectile having a jacket of relatively deformable material which is formed to flare outwardly to comprise the skirt.

The mutual cooperation of adjacent sub-projectiles of the projectile assembly according to the invention may be constructed by forming an axially disposed recess in the rear of the body of each leading sub-projectile said recess being adapted to receive the point of the body of the following sub-projectile, the cooperating area of the adjacent sub-projectiles being adapted to provide mutual support of said sub-projectiles against longitudinal instability. The mutual cooperation of the reflexed skirt forms of sub-projectiles according to the invention may further comprise the contact of the rear annular face of each leading sub-projectile against a mating annulus in the forward face of each following sub-projectile of said assembly. Adjacent sub-projectiles may be further interconnected according to the invention by the bonding together of the cooperating surfaces between adjacent sub-projectiles by means of a metallic or non-metallic material such as an alloy of lead or a plastic such as Teon, such material having the property of rupturing under heavy stress and providing a lubricating quality to assist in the relative separation of the formerly rigidly cooperating surfaces.

.The sub-projectiles of the projectile assembly according to the invention may be formed and assembled in such manner that an annular space is disposed between adjacent sub-projectiles. Said annular space may be fully enclosed between the skirts of adjacent sub-projectiles such as in the case of rearwardly reflexed skirts or said annular space may be enclosed between the forward and rear faces of adjacent following and leading sub-projectiles, respectively, and the bore of the barrel, such as in constructions having simple skirts.

Said annular space between adjacent sub-projectiles of a projectile assembly according to the invention may be left as an air void in which case the violent adiabatic compression of the air, due to the inward squeezing of the sub-projectile skirts which is performed during passage of the projectile assembly along the tapered portion of the barrel bore, is harnessed to force the separation of adjacent sub-projectiles. To supplement the separating pneumatic pressure within said space, the skirt of each following sub-projectile may be provided with means such aS one or more gas passages or peripheral grooves which are adapted to be nipped closed -by the deformation of the skirt during the early phase of the squeeze operation, and via which a quantity of propellant gas may be bled into said space between adjacent sub-projectiles before the squeeze operation. Alternatively, according to the invention, the said space between adjacent sub-projectiles may be lled or partly lled with a quantity of frangible or relatively soft material which is substantially incompressible but which ruptures or iiows under shock stress in such manner as will induce the separation of adjacent sub-projectiles during their propulsion along the tapered portion of the barrel. Alternatively, according to the invention, the said space between adjacent sub-projectiles may be filled or partly filled with a quantity of solid or other propellant of known formulation which may be ignited during propulsion f the projectile assembly within the barrel bore by incandescent ash from the propulsive gasses and/ or by the heat of friction of the projectile assembly within the barrel bore and/ or by the compression ignition of air enclosed within the said space. Alternatively, within the scope of the invention the forced separation of adjacent sub-projectiles of a projectile assembly may be performed by a combination of any of the above described means in accordance with the scale and particular requirements of each application performed within the scope of the invention, and in a manner as above described adapted to impart a substatial relative separating velocity between each adjacent sub-projectile.

In the accompanying drawings:

FIGURE l shows a salvo projectile assembly according to the invention comprising four squeezebore subprojectiles of the form having simple skirts.

FIGURE 2 is an end view on the rear of same.

FIGURE 3 is a longitudinal section along the axis of sub-projectiles of similar form to those of FIGURE 1 just after initiation of shot travel and while in the full bore riiled portion of the barrel.

FIGURE 4 is a si-milar section representing the same projectiles while in the smooth-bore tapered portion of the barrel.

FIGURE 5 is a similar section showing the same projectiles during the final squeeze, and while in the smoothbore sub-caliber portion of the barrel adjacent to the muzzle.

FIGURE 6 is a similar section of an assembly of squeezebore sub-projectiles of a form having reexed skirts.

Referring to FIGURES 1 and 2, the projectile assembly 1 comprises four individual sub-projectiles 2, 3, 4, and 5, each of which is substantially similar in form and each being formed from a single piece of material. Referring to FIGURE 3, each of the said sub-projectiles, for instance, sub-projectile 2 is provided with a body 6, the point 7 of which is flame hardened, and a deformable conical skirt 8. Said skirt is formed to an enlarged diameter and provided with a cylindrically formed rim 9 adapted to lill and engrave in the rifled full bore 10 of the gun, said skirt having a hollow cavity 11 to its rear which is formed in conjunction with the thickness of the skirt 8 in such manner as to accommodate said skirt during the deformation of squeezing. Each of said sub-projectiles is provided with an axially disposed recess 12 which is formed in the rear of the body thereof as shown in subprojectile 5. Said recess formed in each sub-projectile 2, 3, 4, 5 is adapted to closely cooperate with point 7 as shown in sub-projectile 1, of each adjacently disposed subprojectile in such manner as to prevent mutual longitudinal instability. The cooperating areas of all adjacently disposed sub-projectiles are rigidly connected by means of a bond 13 of Teflon.

The annular space 14 included between the skirts of sub-projectile 4 and 5 according to this example is an air-filled void. The skirt 15 of sub-projectile 5 is provided with a gas passage 16 which communicates between the ring chamber volume 17 and the space 14. The annular space 18 included between sub-projectiles 3 and 4 is filled with a deformable plastic material 19 such as synthetic wax. The annular space 20 disposed between sub-projectiles 2 and 3 is partly lled with a quantity of solid propellant 21 of known formulation.

Upon the introduction and locking of the projectile assembly 1, a quantity of propellant (not shown) and an ignition means of known form (not shown) in the breech of the firearm, the sequence of operations of the projectile components within the barrel leading to the propulsion of the individual sub-projectiles from the muzzle of the barrel as a result of discharge, is described with reference to FIGURES 3, 4 and 5. Referring particularly to FIGURE 3, after ignition of the propellant charge, the projectile assembly 1 is propelled along full more 10 of the barrel. The outer rims 9 of the skirts 8 of sub-projectiles 2, 3, 4, 5 engraving in the rifliug of said bore 10 thereby causing the rotation of each of said sub-projectiles in well known manner. Owing to the large area of propulsion presented by the relatively large diameter of projectile assembly 1 with respect to the mass of same, the acceleration of said projectile assembly is relatively greater than that of projectiles of usual density with respect to bore area. During the rst phase of propulsion as shown in FIGURE 3, some of the propellant gasses are vented via passage 16 into space 14.

Referring to FIGURE 4, as projectile asembly 1 proceeds along the smooth convergingly tpered bore 22 of the barrel, the passage 16 is nipped shut thereby trapping a quantity of propellant gas in annular Space 14. As skirts 15 and 8" are squeezed inwardly by action of the tapered bore 22 and the volume of space 14 is accordingly reduced, the violently mounting pressure of air and pr0- pellant gasses trapped in said space forces the separation of subprojectiles 4 and 5. Similarly, as skirts 8" and 8 are squeezed inwardly by action of tapered bore 22, the substantially incompressible plastic material 19 disposed in space 18 is squeezed as a result of the reduction in volume of space 18, thereby forcing apart sub-projectiles 3 and 4. Similarly, as skirts 8 and 8 of sub-projectiles 2 and 3 respectively are inwardly deformed by their passage along the tapered bore 22 the violent compression of air locked in space 20 causes the compression ignition of propellant 21 thereby providing gas pressure which greatly assists in the separation of sub-projectiles 2 and 3.

As the projectile assembly 1 leaves the rifled full bore of the barrel it is spinning rapidly due to the action of the riing therein in well known manner. As subprojectiles 2, 3, 4, 5 of said assembly proceed along the smooth tapered bore 22 of the barrel, the reduction in the rotational mass moment of inertia in each said sub-projectile substantially increases its rate of spin due to the principle of conservation of momentum. The stability derived from such spin together with the increasing peripheral area of the rim 9 of each skirt 8 in contact with the tapered bore 22 of each said sub-projectile as it proceeds along the converging taper provides the longitudinal stability of the said sub-projectiles following their separation.

Referring to FIGURE 5, as sub-projectiles 2, 3, 4, 5 leave the sub-caliber end of the tapered bore 22 and enter cylindrical sub-caliber bore 23, the Skirts 8 have been deformed inwardly so that their peripheral diameter substantially equals that of the body 6 of the said sub-projectiles. As the said sub-projectiles, such as subprojectile 1 in FIGURE 5, leave the muzzle 24 of the sub-caliber bore 23, each said sub-projectile: has been reduced by inward deformation to have substantial density with respect to its area, has been imparted unusually high velocity, is stable owing to its high rate of spin, and is not influenced in its accuracy as in known forms of salvo ammunition by muzzle blast by reason 0f the sequential and symmetrical nature of the ejection of the salvo of projectiles and their propellant gasses.

It will be clearly recognized that within the scope of the invention any combination of the above devices for separating the several sub-projectiles in each projectile assembly may be used in each projectile assembly form. For instance, spaces 14, 18 and 20 may all be filled or partly filled with a substantially incompressible, relatively lightweight deformable or frangible material. Alternatively, such spaces may be left as air voids. Alternatively, such spaces may be provided with a quantity of propellant of known formulation. Alternatively, following skirts such as skirts 15, 8" and 8 may be provided with one or more peripheral grooves or passages similar to passage 16 of skirt to enable the bleeding of a quantity of propellant gasses into the 'spaces between said sub-projectiles.

Referring to FIGURE 6, constructions according to this example are usually preformed in firearm forms wherein there is a relatively large full bore to sub-caliber bore ratio. According to this example substantially more mechanical cooperation is made available between adjacent sub-projectiles of a projectile assembly thereby increasing their mutual support potentialities during propulsion within the gun, for the purpose of preventing deformation or rupture of the rearmost sub-projectile(s) in such firearm forms.

According to the example as shown in FIGURE 6, the sub-projectiles 25, 26, 27, 28 are substantially similar, and each is provided with a skirt 29, such skirt`having a cylindrical element 30 disposed adjacent to the cylindrical outer rim 31 of said skirt. Said cylindrical elements are formed to extend rearwardly and to cooperate with forward annular face 32 of the similar skirt of the adjacent following sub-projectile. The cooperating area between cylindrical element 30 and annular face 32 are rigidly connected with a bond of Teflon.

`In all other respects the sub-projectiles according to this example are similar to that according to FIGURES 1 and 2 except in that according to the present example the body 33 of each similar sub-projectile comprises a hardened core 34 around which is formed a jacket 35 which is formed to include the skirt 29 and the cylindrical element 30 as above described.

Furthermore, for the purposes of clarity the same means are employed in the example according to FIG- URE 6 for separating the sub-projectiles 25, 26, 27, 28 as were used in the example according to FIGURES 1 and 2, the sequence of operations as the projectile assembly proceeds along the bore thereby being similar to that shown in FIGURES 3, 4 and 5. According to this example, however, the cooperation of the rear faces of cylindrical elements 30 with the forward annular faces 32 of skirts 29, also provides additional separating force.

It will be recognized that in the above examples the number of sub-projectiles comprising each projectile assembly may embrace from two sub-projectiles to the maximum number which is practicable according to the requirements and conditions of each application according to the invention.

What I claim is:

1. A projectile assembly for use in squeezebore firearms comprising, a plurality of coaxially arranged subprojectiles each having an axially disposed body and a radially extending deformable annular flange, means' on the flange of each of said subprojectiles for sealingly engaging the squeezebore of a firearm to provide a hermetically sealed -deformable cavity between each pair of adjacent subprojectiles, and a readily deformable material in each of said cavities to effect separation of adjacent subprojectiles upon deformation of said cavities as said assembly is radially squeezed in said squeezebore.

2. A projectile assembly for use in squeezebore firearms comprising, a plurality of coaxially arranged subprojectiles each having an axially disposed body and an outwardly extending deformable annular flange, means on the flange of each of said subprojectiles for sealingly engaging the squeezebore of a firearm to provide a hermetically sealed deformable cavity between each pair of adjacent subprojectiles, and a readily deformable material in each of said cavities responsive to predetermined movement of said assembly through said squeezebore to elongate said cavities and thereby effect separation of adjacent subprojectiles.

3. A projectile assembly for use in squeezebore firearms comprising, a plurality of subprojectiles each of which is formed Iwith a body having complementally shaped generally convex forward and concave rearward end portions, said subprojectiles being coaxially arranged in mating engagement with adjacent subprojectiles having the forward end portion of one su-bprojectile within the rearward end portion of the other, a deformable annular flange extending radially from each of said bodies for sealing engagement with the squeezebore of a firearm to thereby provide a hermetically sealed deformable annular cavity about the mating engagement of adjacent subprojectiles, and a readily deformable material in each of said annular cavities to effect separation of adjacent subprojectiles as the flanges and cavities are radially deformed during movement of said assembly through said squeezebore.

4. A projectile assembly for use in squeezebore firearms comprising, at least two substantially identical subprojectiles coaxially arranged initially in predetermined relative positions, each of said subprojectiles having reduced body portions carrying radially extending deformable sealing means for circumferentially engaging the squeezebore of a firearm throughout travel of said assembly therethrough, the sealing means of adjacent subprojectiles forming a deformable hermetically sealed cavity between each pair of adjacent subprojectiles, whereby travel of said assembly through said squeezebore causes said sealing means and cavities to be radially reduced so as to affect axial elongation of said cavities and hence corresponding axial separation of adjacent subprojectiles, each of said cavities being filled with a readily deformable material to cause said cavities to -be elongated upon radial reduction thereof.

(References on following page) References Cited UNITED STATES PATENTS Scott 102-38 Greener 102-38 Janecek et al. 42--76 Kulluck 102-38 Barnard 102,-42 Russell 102,-92 X Hurst 102-925 FOREIGN PATENTS `663,288 8/1938 Germany.

SAMUEL FEINBERG, Primary Examiner.

5 JAMES FOX, Assistant Examiner.

U.S. C1. X.R. 

1. A PROJECTILE ASSEMBLY FOR USE IN SQUEEZEBORE FIREARMS COMPRISING, A PLURALITY OF COAXIALLY ARRANGED SUBPROJECTILES EACH HAVING AN AXIALLY DISPOSED BODY AND A RADIALLY EXTENDING DEFORMABLE ANNULAR FLANGE, MEANS ON THE FLANGE OF EACH OF SAID SUBPROJECTILES FOR SEALINGLY ENGAGING THE SQUEEZEBORE OF A FIREARM TO PROVIDE A HERMETICALLY SEALED DEFORMABLE CAVITY BETWEEN EACH PAIR OF ADJACENT SUBPROJECTILES, AND A READILY DEFORMABLE MATERIAL IN EACH OF SAID CAVITIES TO EFFECT SEPARATION OF ADJACENT SUBPROJECTILES UPON DEFORMATION OF SAID CAVITIES AS SAID ASSEMBLY IS RADIALLY SQUEEZED IN SAID SQUEEZEBORE. 